1. Field of the Invention
The present invention relates to a thermal development diazo copying material capable of developing latent images formed thereon with the application of heat thereto, which latent images are formed with the thermal development diazo copying material being exposed to light with a transparent or semitransparent image-bearing original being superimposed thereon on the thermal image development diazo copying material. The present invention also relates to a thermosensitive recording material on which images can be fixed by the application of light thereto.
2. Discussion of Background
A conventional thermal development diazo copying material is generally composed of a support such as a sheet of paper, or a film, and a photosensitive layer formed thereon, which is mainly composed of a diazo compound, a coupling component, and a coloring auxiliary agent. As such a coloring auxiliary agent, for example, urea and sodium trichloroacetate are employed.
In any diazo copying materials of this kind, latent images are developed by the application of heat to 180.degree. to 200.degree. C. In these copying materials, an alkaline component formed by thermal decomposition of the coloring component contained therein is utilized in the development mechanism.
In an attempt to decrease the development temperature, for instance, down to 90.degree. to 130.degree. C., a thermofusible material, such as a higher fatty acid amide, is employed as a coloring auxiliary agent. In this development mechanism, the activation of a diazo compound and a coupling component by the thermal fusion thereof is utilized.
However, conventional thermal development diazo copying materials have the shortcoming that the precoupling of a diazo compound and a coupling component gradually proceeds to become colored during the preservation thereof.
In order to eliminate this shortcoming, it has been proposed that one of a diazo compound, a coupling component or an alkaline generating agent is contained in the form of discontinuous particles to prevent the mutual contact of the above components, thereby avoiding the precoupling, for instance, in Japanese Laid-Open Patent Applications 57-42042, 57-45094, and 57-125091.
However, when the particles of the above components are reduced in size in order to obtain high thermo-sensitivity in the thermal development diazo copying materials of the above-mentioned type, the problem that the preservability thereof is significantly decreased is caused.
In Japanese Patent Publication 4-75147, a capsuling technique is proposed in which only a diazo compound is used as a core material for microcapsules made of polyurethane or polyurea by polymerization so as to cover the diazo compound. Since the agent for making such a separation wall of the microcapsules is a thermosetting resin, an alkaline generating agent has to be employed in order to attain an appropriate thermosensitivity for use in practice.
Furthermore, since the diazo compound is contained in the microcapsules, the application of ultraviolet light to the diazo compound is hindered by the walls of the microcapsules which are made of polyurethane or polyurea, so that when a thermal development diazo copying material using such microcapsules is employed in a copying machine, a light source with a large capacity has to be employed. This is a fatal shortcoming of this microcapsule technique.
Furthermore, Japanese Laid-Open Patent Application 57-44141 proposes an in-liquid drying method by which a coupling component or a coloring auxiliary agent is capsuled by a non-polar wax-like material. A thermal development diazo copying material prepared by this method, however, has so high a coloring sensitivity that fogging is formed in the thermal development copying material even when exposed to air in the summer. Thus, this thermal development diazo copying material has several problems with respect to the control of its coloring temperature when used in practice.